Everytime I try to use the command I get a popup that says you dont have permissoin to do this. Every time I try to give myself permissoin I get the error vanish.use doesn't exist. I have myself as an admin. Im not sure how to fix this. 

did you figure this out?

It's in the server console when you do o.grant "user/group" [...] vanish.use??

Or InGame, when you try the disappear command?